"Chargers chaplain Shawn Mitchell said he was notified of the death and is on his way to be with family members."

According to The Associated Press, police in Oceanside, Calif., confirm Seau's death and have said he was found with a gunshot wound to the chest. He was 43.

The Chargers team has posted messages on its Twitter page saying "everyone at the Chargers is in complete shock and disbelief right now. ... We ask everyone to stop what they're doing and send their prayers to Junior and his family."

If Seau did commit suicide by shooting himself in the chest, comparisons will be made to the February 2011 death of former Chicago Bears safety Dave Duerson. Before shooting himself in the chest, Duerson wrote a note asking that his brain be studied for chronic traumatic encephalopathy — a disease linked to depression. As NPR's Tom Goldman reported at the time, some NFL retirees have shown signs of the disease.

Update at 3:45 p.m. ET. Police Say It's Being Investigated As A Suicide:

Oceanside Police Chief Frank McCoy just told reporters outside Seau's home that the former player was found by a woman who said she was his girlfriend. He was still alive, but "suffering from a gunshot wound to the chest," McCoy said. "A handgun was found near the body."

Efforts to save Seau were unsuccessful.

The case, McCoy said, is "being investigated as a suicide."

Moments before McCoy spoke, Seau's mother made an emotional appearance at the microphone. "I don't know who do this to my son!" she said. "Take me!"